Essays on spatial economics

What are the causes and consequences of the spatial variation of economic activities both within and across cities? To contribute to our understanding of this question, the two chapters in this PhD thesis seek to advance two research agendas. The first is an understanding of the causes of the spatial variation in structural transformation in a country and how this affects spatial inequality and the upward income mobility of workers. The second is addressing the mechanisms that shape the internal structure of a city in a developing country. The approach to both is a mix of theory and empirics, leveraging the structure of the model for identification. The first chapter develops a dynamic overlapping generations model of economic geography to explain variation in structural transformation across space and time. Despite the heterogeneity across locations, sectors, and time, the model remains tractable and is calibrated to match metropolitan area data for the U.S. economy from 1980 to 2010. The calibration allows us to back out measures of upward mobility and inequality, thereby providing theoretical underpinnings to the geographical variation of upward mobility and spatial inequality. The counterfactual analysis shows that structural transformation in the last decades has had substantial effects on mobility. The second chapter studies how quantitative urban models can be calibrated in the data-sparse environments in developing countries using data from Dhaka. In particular, this paper shows how newly available satellite data on building heights can be used to estimate the housing supply elasticity. With the model parameters, we can also estimate the price of land and floor space in the city, which are prices that are usually difficult to observe for cities in developing countries directly. This paper also presents model counterfactuals to illustrate how essential it is to understand the general equilibrium impacts of the policy change

Policy of airline competition ~monopoly or duopoly~

We show that monopoly is better than competition in term of social welfare for low frequency routes. Competition affects both flight schedules and airfares. Flight schedules get un-even interval by competition and this leads to large scheduling delay cost (SDC). The increment of SDC is large when the number of flights is small. For low frequency routes, the increment of SDC by competition overwhelms the decreasing in the airfare, so monopoly is better than competition

Policy of airline competition ~monopoly or duopoly~

We show that monopoly is better than competition in term of social welfare for low frequency routes. Competition affects both flight schedules and airfares. Flight schedules get un-even interval by competition and this leads to large scheduling delay cost (SDC). The increment of SDC is large when the number of flights is small. For low frequency routes, the increment of SDC by competition overwhelms the decreasing in the airfare, so monopoly is better than competition

User Impressions of System Questions to Acquire Lexical Knowledge during Dialogues

We have been addressing the problem of acquiring attributes of unknown terms through dialogues and previously proposed an approach using the implicit confirmation process. It is crucial for dialogue systems to ask questions that do not diminish the user’s willingness to talk. In this paper, we conducted a user study to investigate user impression for several question types, including explicit and implicit, to acquire lexical knowledge. We clarified the order among the types and found that repeating the same question type annoys the user and degrades user impression even when the content of the questions is correct. We also propose a method for determining whether an estimated attribute is correct, which is included in an implicit question. The method exploits multiple-user responses to implicit questions about the attribute of the same unknown term. Experimental results revealed that the proposed method exhibited a higher precision rate for determining the correctly estimated attributes than when only single-user responses were considered

A comparative analysis of attitudes toward genome-edited food among Japanese public and scientific community

Shineha R., Takeda K.F., Yamaguchi Y., et al. (2024) A comparative analysis of attitudes toward genome-edited food among Japanese public and scientific community. PLoS ONE 19(4): e0300107. doi:10.1371/journal.pone.0300107.Genome editing technologies such as CRISPR/Cas9 have been developed in the last decade and have been applied to new food technologies. Genome-edited food (GEF) is a crucial issue with those new food technologies. Thus, each country has established GEF governance systems to maximize benefits and minimize risks. These emphasize the importance of communicating about GEF to the public. The key concerns are understanding various viewpoints and value perspectives (framings) in science and technology and encouraging and opening communication with the public. Thus, it is essential to understand differences between the public and experts’ interests and discuss various framings and effective communication with regard to GEF. Accordingly, this study involved administering a questionnaire to analyze the public’s attitudes in Japan and identify gaps between these and expert opinions on GEF. A total of 4000 responses from the public and 398 responses from GEF experts were collected. The study found that the Japanese public has a “wait- and-watch” attitude toward GEF, and the demand for basic information on it is quite high. Moreover, they are apprehensive about proper risk governance systems for GEF. This is despite experts’ emphasis on the adequacy of the mechanism, necessity of technology, and trust in the scientific community. Understanding gaps between the public and experts’ opinions on and interests in GEF provides essential insight for effective communication and acts as the basis for appropriate governance of emerging science and technology

Influence of Ultrasonic-Shot Peening on Bending Fatigue of TiNi Shape Memory Alloy

The fatigue property of shape memory alloy (SMA) is one of the most important subjects in view of evaluating functional characteristics of SMA elements. In the present study，ultrasonic shot peening (USP) was applied to induce compressive residual stress on the surface layer of TiNi SMA tape and the influence of USP on the bending fatigue life was investigated. The fatigue life of USP-treated tape is longer than that of the as-received tape. The fatigui life of the tape USP-treated with high coverage is longer than that with low coverage. The fatigue life of the USP-treated tape increases in proportion to the hardness on the surface of the tape